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Revert "Reapply "[PR16756] Use SSAUpdaterBulk in JumpThreading." one more time."

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This reverts commit r329865. Causes stage2/stage3 miscompare.

llvm-svn: 329910
This commit is contained in:
Benjamin Kramer 2018-04-12 13:52:02 +00:00
parent 51cf026a91
commit a88123dd3d
1 changed files with 13 additions and 18 deletions
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31
lib/Transforms/Scalar/JumpThreading.cpp
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@ -66,7 +66,6 @@
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/Cloning.h"
#include "llvm/Transforms/Utils/SSAUpdater.h"
#include "llvm/Transforms/Utils/SSAUpdaterBulk.h"
#include "llvm/Transforms/Utils/ValueMapper.h"
#include <algorithm>
#include <cassert>
@ -1990,13 +1989,9 @@ bool JumpThreadingPass::ThreadEdge(BasicBlock *BB,
// now have to update all uses of the value to use either the original value,
// the cloned value, or some PHI derived value. This can require arbitrary
// PHI insertion, of which we are prepared to do, clean these up now.
SSAUpdaterBulk SSAUpdate;
SSAUpdater SSAUpdate;
SmallVector<Use*, 16> UsesToRename;
unsigned VarNum = 0;
for (Instruction &I : *BB) {
UsesToRename.clear();
// Scan all uses of this instruction to see if it is used outside of its
// block, and if so, record them in UsesToRename.
for (Use &U : I.uses()) {
@ -2013,15 +2008,19 @@ bool JumpThreadingPass::ThreadEdge(BasicBlock *BB,
// If there are no uses outside the block, we're done with this instruction.
if (UsesToRename.empty())
continue;
SSAUpdate.AddVariable(VarNum, I.getName(), I.getType());
// We found a use of I outside of BB - we need to rename all uses of I that
// are outside its block to be uses of the appropriate PHI node etc.
SSAUpdate.AddAvailableValue(VarNum, BB, &I);
SSAUpdate.AddAvailableValue(VarNum, NewBB, ValueMapping[&I]);
for (auto U : UsesToRename)
SSAUpdate.AddUse(VarNum, U);
VarNum++;
DEBUG(dbgs() << "JT: Renaming non-local uses of: " << I << "\n");
// We found a use of I outside of BB. Rename all uses of I that are outside
// its block to be uses of the appropriate PHI node etc. See ValuesInBlocks
// with the two values we know.
SSAUpdate.Initialize(I.getType(), I.getName());
SSAUpdate.AddAvailableValue(BB, &I);
SSAUpdate.AddAvailableValue(NewBB, ValueMapping[&I]);
while (!UsesToRename.empty())
SSAUpdate.RewriteUse(*UsesToRename.pop_back_val());
DEBUG(dbgs() << "\n");
}
// Ok, NewBB is good to go. Update the terminator of PredBB to jump to
@ -2038,10 +2037,6 @@ bool JumpThreadingPass::ThreadEdge(BasicBlock *BB,
{DominatorTree::Insert, PredBB, NewBB},
{DominatorTree::Delete, PredBB, BB}});
// Apply all updates we queued with DDT and get the updated Dominator Tree.
DominatorTree *DT = &DDT->flush();
SSAUpdate.RewriteAllUses(DT);
// At this point, the IR is fully up to date and consistent. Do a quick scan
// over the new instructions and zap any that are constants or dead. This
// frequently happens because of phi translation.